1. Field Of The Invention
The invention pertains to a transparent thermoplastic thermostat housing for providing a visual indication of the precise operation of the engine thermostat in all phases of engine operation. More particularly the invention pertains to a transparent thermoplastic housing which may include optically enhanced surfaces for magnifying the visual display of the thermostat within the transparent housing to provide direct visual confirmation of the operation of the thermostat by providing direct visual access to the thermostat through the engine coolant or by imparting a churning action to the coolant where the coolant is highly colored or opaque.
The transparent thermoplastic housing may be disposed between sections of radiator hose or may include provision for direct mounting to the engine block. In all such applications the transparent thermoplastic housing includes means for engaging the annular flange of the thermostat and maintaining the thermostat in a proper orientation to the direction of flow of engine coolant. The transparent housing for the engine thermostat may be constructed in a variety of configurations for capturing the engine thermostat and may be of one or more piece construction. The housing assists in maintaining the thermostat in place and providing visual access to the thermostat and providing disrupted flow of the coolant to confirm the proper operation of the thermostat.
The transparent thermostat housing may be placed in line that is between sections of radiator hosing or be placed against the engine block to provide the advantages of visual confirmation as to the status and operation of the thermostat as well as the condition of the engine coolant under all engine operating conditions. The transparent thermoplastic housing may be constructed of thermoplastic materials such as transparent polyurethanes and polycarbonates and other transparent plastics which are thermally stable and translucent. The transparent thermoplastic housing may be covered by an optional protective sleeve made of canvas, fabric, fiberglass, rubber, plastic or the like to protect the outside surface of the viewable thermostat from oil, grease, dust and debris so the flowing motion of the engine coolant as well as the operation of the thermostat can be visually detected without requiring cleaning particularly where such operation is in dusty or greasy environments.
2. Description Of The Prior Art
The prior art includes a wide variety of thermostat housings for use in controlling the temperature of internal combustion engines. The thermostat housing is generally contained between the engine block and a metal pipe having a flange which is bolted to the engine block. The metal pipe is then connected to the radiator inflow hose to transport hot engine coolant to the radiator. An example of such a prior art setup is shown in Schroeder U.S. Pat. No. 4,327,673.
More recently applications have been introduced for in-line thermostats which include a thermostat housing which is connected between sections of the radiator in-flow hose such as illustrated in Hovey U.S. Pat. No. 4,583,499. In other prior art such as Reynolds U.S. Pat. No. 4,993,628 and 5,123,591 special radiator out-flow hoses have been constructed to engage the thermostat in a position in the radiator hose. This prior art has the advantage of providing improved access to the thermostat for maintenance but does not provide visual access for determining whether the thermostat is operating properly.
In all prior art applications the thermostat has been engaged in either a housing or section of the radiator inflow hose or in the engine block under a metallic pipe making visual access to the thermostat and the engine coolant impossible without disassembly. In all prior art applications the position and operation of the thermostat and the condition of the engine coolant has been hidden behind or in metal housings or rubber hoses or other opaque structures. As a result it has heretofore been impossible to visually determine the condition of the engine coolant and whether the thermostat was operating properly or if it remained in its proper position.
In the past the proper operation of the thermostat could only be confirmed by a mechanic who would operate the engine and feel the radiator hose when the engine reached operating temperature. The problems of determining the proper operation of the thermostat were further aggravated by the temperature and pressures under which internal combustion engines operate together with the chemical composition of the coolant or antifreeze as well as the contaminants that make their way into the cooling system and the radiators over the operating life span of the engine coolant. The possibility of leaks in the cooling system coupled with the introduction of hydrocarbons, acids and other contaminants into the cooling system through bad engine gaskets have heretofore required the use of metal or rubber or housing materials that were opaque making the thermostat not visible.
For most engines the coolant not only contains various types of antifreeze but also is pressurized at a pressure from 6 to 20 psi and operates in ambient temperature ranges from arctic conditions to equatorial conditions which require the thermostat to open once the engine reaches a predetermined temperature which is generally 160, 180 or 212 degrees Fahrenheit. Added to these environmental conditions of course is the chemical composition of the coolant together with the condition of the internal combustion engine and the thermal and mechanical considerations of the system which has resulted in the prior art not utilizing a transparent housing for the engine thermostat.
The temperature, pressure and operating conditions together with the mechanical configurations of engine thermostats has generally required the thermostat to be mounted between the engine block and a curved metal fitting in order to maintain the thermostat in place during operating conditions. The adverse pressures and temperatures encountered in operating conditions has resulted in many in-line applications not being accepted due to the temperature and pressure parameters and the expansion and contraction encountered in typical rubber hoses as a result of the pressure and temperature variations and the possibility of the thermostat becoming dislodged. In other such applications a change in diameter of the in-line thermostat housing has been used to maintain the thermostat housing in a housing made of steel or other appropriate material which housing is then covered with the rubber radiator hose such as in Hovey U.S. Pat. No. 4,583,499 for in-line thermostat applications.
The extremes in temperature and pressure conditions encountered together with the mechanical forces necessary to maintain the thermostat in position has generally required the placement of the thermostat in the engine block and has resulted in transparent plastic being an unacceptable material due to the corrosive nature of the engine coolant coupled with the temperatures, pressures and mechanical considerations. These mechanical considerations not only include thermal expansion and contraction but also mechanical forces necessary to hold the housing in place. These mechanical considerations together with the chemical considerations of the coolant has resulted in plastic and particularly transparent plastic not being considered as being suitable materials for use in combination with engine thermostats.
The invention is the result of an extensive research investigation into transparent thermoplastic materials and in contrast to the prior art employs a thermoplastic transparent plastic for use as a viewable housing to provide visual confirmation as to the proper operation of the engine thermostat. The invention not only provides for visual access to the thermostat where the coolant is clear or lightly colored but also provides visual indication of the proper operation of the thermostat by providing visual access to the disturbed flow of engine coolant where the coolant is heavily colored or opaqued by engine contamination. In addition it has been found that certain transparent visible thermostat housings may be utilized and operate in the mechanical, chemical extreme conditions encountered in internal combustion engines. The transparent thermoplastic materials not only withstand the operative environments but also do not become discolored, distorted or opaqued by the engine coolant to provide visual confirmation of the thermostat in all phases of the engine operation and provides visual confirmation of the status of the engine coolant.